Telemetric system



c. s. FRANKLIN TELEMETRIC SYSTEM Filed Oct. 5. 1929 Wu [0 w h u w m M WP m u m w m m. 0 O t t w w m m s 5 Slow to release ,0

Slow to release Inventor.

ChWFranKlin, b l/beav (H Hi6 Attorney.

Patented Feb. 13, 1934 UNITED STATES TELEMETRIC SYSTEM Charles S.Franklin, Hollywood, Calif., minor to General Electric Company, acorporation of New York Application October 5, 1929. Serial no; 397,01:

7 Claims.

My invention relates to telemetric systems and has for its object toefiect certain improvements in the receiving systems used in connectiontherewith.

Telemetric systems are now known in the operation of which currentimpulses are transmitted in succession over a telemetering channel, eachimpulse corresponding to a particular meter, or other device, orelement, the reading or condition of which is to be remotely indicated,and comprising current having a characteristic determined in accordancewith the position or condition of the corresponding device. Means areprovided in connection with systems of this type whereby a plurality ofreceiving instruments are connected to the channel in succession eachconnection being made in response to an interruption of current betweenimpulses. In this way each receiving instrument may be caused to respondto current having a characteristic determined in accordance with acorresponding transmitting element. Such a system is disclosed incopending application Serial No. 202,961, Alan S. Fitzgerald, filed July1, 1927, Patent No. 1,849,827, issued March 15, 1932, entitledTelemetric system and which is assigned to the same assignee as mypresent application.

One of the objects of my invention is to pro; vide means whereby thereceiving instruments are each connected to the channel only during itsappropriate impulse when current having a characteristic determined inaccordance with a corresponding transmitting element is received. Inthis way, any false deflection of the different receiving instruments asdue to being connected to the channel during a portion of an impulsewhen the character of the received current is determined by anon-corresponding transmitting element, is avoided.

The novel features which I believe to be characteristic of my inventionare set forth with particularity in the appended claims. My invention,itself, however, both as to its organization and method of operationtogether with further objects and advantages thereof may best beunderstood by reference to the following description taken in connectionwith the accompanying drawing in which Fig. 1 represents an embodimentof my invention and Fig. 2 represents a modification thereof.

Referring to Fig. 1 of the drawing, I have indicated at 1 a line whichmay be used for telemetering purposes. This line may comprise theconductors of a power distribution system over which carrier currentimpulses are transmitted in succession; each-impulse being modulated,for example, with current having a frequency determined in accordancewith the position of a movable element at the transmitting station theposition of which is to be remotely indicated. The

transmitting system may be arranged, as indicated, in the abovementioned application, to transmit impulses of this nature successively,and successive impulses being modulated in accordance with the positionof the different transmitting elements sequentially and in rotation.These carrier currents are received through coupling condensers 2 andare impressed in the usual way upon the grid of an electron dischargedetector 3. The modulating currents resulting from detection of thereceived carrier currents are supplied from the anode circuit of thedetector 3 through a transformer 4, and switching elements 5 and 6 tothe different receiving instruments '7, 8, 9, 10, 11, etc., dependentupon the position which the switch elements 5 and 6 occupy. Theinstruments '7, 8, 9, 10, 11 may comprise frequency responsiveindicating devices each of which responds to the frequency of currentwith which the corresponding received carrier impulse is modulated,thereby to indicate the position of the corresponding remote element.

The switch elements 5 and 6 comprise wipers of a selector switchdesignated as a whole as 12 on the drawing. This selector switch has amotor magnet 13 which is adapted; through a suitable ratchet and pawlarrangement, upon each deenergization thereof to actuate the wipers ofthe selector switch from their instant position to the next succeedingposition thereby to connect the various meters '7, 8, 9, etc., to thereceiving channel in succession. Relays 15, 16 and 1'7 are provided tocontrol the energization of motor magnet 13 and to cause deenergizationthereof in response to each successive interruption in the receivedcarrier.

The operation of the system is as follows: The relays 15, 16 and 1'7 andthe selector switch 12 are shown in the position which they occupy whenthe carrier has been interrupted for a predetermined interval longerthan. the interruptions which occur between impulses, the receivinginstrument '7 being connected to the carrier channel. During an impulseof received carrier the current in the anode circuit of detector 3increases causing operation of relays 15 and 16. The alternating currentresulting from demodulation of the received carrier impulse will then besupplied through transformer 4 and switching elements 5 and 6 toreceiving instrument '7. When the carrier is interrupted for apredetermined short interval of time, as between the successiveimpulses, a circuit will be completed, due to the slow releasingcharacter of relay 16, which extends from positive potential at thearmature of relay 15 through left hand armature 18 of relay 16 and itsleft hand contact, motor magnet 13 and armature of relay 1'7 to thenegative side of the source of potential. The motor magnet 13 will thenoperate its pawl to a position such that when deenergized the switchwill be operated to the next position. A circuit will also be completedthrough the right hand contacts of relay 15, right hand armature andcontact of relay 16 and winding of relay 17. As stated above these lasttwo circuits are completed due to the fact that relay 16 is slow torelease and does not operate its armature to the right hand positionuntil a predetermined time interval following the deenergization ofrelay 15. This time interval is such that this relay does not operateduring the short interruptions between impulses. After a certainpredetermined interval following energization of relay 17, its armatureis attracted thereby interrupting the circuit of motor magnet 13 andcausing operation of the selector switch thereby to connect receivinginstrument 8 to the carrier channel. When the carrier is again received,as during the next impulse the armature of relay 15 will be operatedagain to the left. The position of the armature of relay 16 however willbe unchanged. Relay 1'7 will be deenergized and will actuate itsarmature to the position shown. When the carrier is again interruptedthe foregoing cycle of operations will again take place resulting in thereceiving instrument 9 being connected to the telemetering channel. Thetime required for the relay 17 to actuate its armature after potentialis applied to its winding is such that the motor magnet 13 has time tobecome fully energized after deenergization of relay 15 and such thatmotor;magnet 13 is again deenergized and has sufiicient'time to causeoperation of selector switch before carrier is again received.Inductance 22 may if desired, be inserted in circuit of relay 1'7 to aidin obtaining this time delay characteristic.

In this way, each of the receiving meters is connected to the carrierchannel 'prior to the initiation of its corresponding carrier impulse.It will be apparent that were this not the case and were the arrangementsuch that the selector switch is operated to its succeeding positionafter initiation of the succeeding impulse, each meter would beconnected to the carrier channel during a portion of an impulse duringwhich the modulation frequency is determined by a non-correspondingtransmitting element and accordingly the meter would be seen to deflectone way or the other just prior to each operation of the selectorswitch, the deflection having a direction dependent upon the position ofthe next element the position of which is to be transmitted.

When the carrier is interrupted for a predetermined interval longer thanthe intervals between the various telemetering impulses, relay 16 willdeenergize and complete a circuit extending from positive potential atthe armature of relay 15 through left hand armature 18 of relay 16 andits right hand contact, upper wiper of switch 12 and its cooperatingbank of contacts, all except the normal contact of which are connectedtogether, interrupter contacts and motor magnet 13. to negativepotential at the armature of relay 17. This circuit constitutes a buzzercircuit for the motor magnet 13 causing the motor magnet to operateswitch 12 to its normal position where the buzzer circuit is interruptedby the upper wiper of the bank 12 engaging in its normal contact. Thusit will be seen that at the end of each transmission period when theposition of each of a plurality of movable elements have beentransmitted in succession by means of impulses separated byinterruptions having a predetermined time interval oi duration a longerinter- -the switch 12 engages its normal contact.

ruption may be produced during which the receiving system will berestored to its normal position thereby connecting a predeterminedmeter, as for example, the meter '7, to the telemetering channel inreadiness for the next cycle of operations.

In the modification of my invention shown in Fig. 2 a pair of contactsof relay 20 are included in a common portion of the circuit of thereceiving instruments this relay being so controlled that it completesthe connection of each of the meters to the telemetering channel at aproper time to avoid the undesired results pointed out above. In thisfigure the lower wiper of selector 12 is also arranged to connectsuccessively each of a plurality of signal lamps in circuit with asource of potential 23 simultaneously with the connection of-acorresponding receiving instrument to the receiving channel; thelighting of the lamp indicating that the corresponding instrument isthen connected to the receiving channel.

The operation of this form of my invention is as follows: The system isshown in the condition which it assumes when an interruption longer thanthe interruptions between carrier impulses has occurred. During thefirst carrier impulse relay 15 will be energized and will operate itsarmature to the left thereby energizing relay 19. This relay is slow torelease such that upon the first interruption of the carrier, a circuitis completed extending from the positive side of the source of potential21 through the armature of relay 15 and its right hand contact, armatureof relay 19 and its left hand contact and the windings of relay 20 andmotor magnet 13 connected in parallel to the negative side of the sourceof potential. Relay 20 then operates and immediately disconnects themeter '7 from the carrier channel. Motor magnet 13 becomes energized andactuates its pawl to a position such that when the motor magnet becomesdeenergized the selector switch will be operated to the next position.When the succeeding carrier impulse is received the above traced circuitis interrupted at the contacts of relay 15 and motor magnet 13 and relay20 become deenergized. Motor magnet 13 immediately operates the selectorswitch to the next position thereby connecting receiving instrument 8 tothe carrier channel. Relay 20 then releases its armature and completesthe circuit of the instrument 8. This relay is sufficiently slow torelease however to permit the complete operation of the selector switchbefore the circuit of the instrument to be connected to the channel iscompleted. In this way all transient effects are eliminated and eachreceiving instrument is connected to the carrier channel only during itsappropriate carrier impulse. When the position of all the remoteelements has been indicated and an interruption, longer than those whichoccur between impulses, occurs, relay 19 will be deenergized therebycompleting a circuit extending from the positive side of the source ofpotential through the armature and right hand contact of relay 15,armature and right hand contact of relay 19, upper wiper and associatedbank of contacts of selector switch 12 interrupter contacts and motormagnet 13 to the negative side of the source of potential.

This circuit constitutes a buzzer circuit for the motor magnet 13causing it to operate the selector switch to its normal position wherethe buzzer circuit is interrupted when the upper wiper of The system isthen in readiness for the next cycle of indications.

While I have shown particular embodiments of my invention, it will beunderstood that many modifications may be made both in the circuitarrangement and in the instrumentalities employed and I contemplate bythe appended claims to cover any such modifications as fall within thetrue spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

l. The combination, in a telemetric system in which current impulses aretransmitted through a telemetering channel, each impulse having. afrequency determined in accordance with the condition of an element tobe remotely indicated, and said impulses being separated bypredetermined time intervals, of a plurality of frequency "responsiveindicating devices located at the point where indications are to bemade, and means responsive to the interruptions between impulses forsuccessively connecting said indicating devices to said channel, wherebycurrents from said channel are received by said indicating devices, saidmeans being operable to disconnect each indicating device from thechannel before the succeeding impulse begins.

2. The combination, in a high frequency telemetering system, of a highfrequency receiver, a plurality of receiving instruments, means forsuccessively connecting each of said instruments to the output circuitof said high frequency receiver, each connection beingmade in responseto an interruption between impulses 9f the received high frequency,whereby eachl receiving instrument is connected to the receiver duringan appropriate impulse of received high frequency and means fornormally, preventing any instrument from being connected to the receiverduring any impulse other than the one appropriate to the particular instrument.

3. The combination, in a telemetric system in which current impulses aretransmitted through a telemetering channel, each impulse having afrequency determined in accordance with the position of an element to beremotely indicated, of a plurality of frequency responsive indicatingdevices, means including a step by step selector switch for successivelyconnecting said indicating devices to the channel, said switch having aplurality of positions and a stepping magnet, means responsive to aninterruption in current in said channel to energize said magnet, andmeans operable subsequently to deenergize said magnet thereby to causesaid switch to operate to its next position, and time delay means forcausing the connection of each meter to the channel to be interruptedbefore the succeeding impulse begins.

4. The combination, in a telemetric system in which current impulses aretransmitted through a telemetering channel, each impulse having afrequency determined in accordance with the position of an element to beremotely indicated, of a plurality of frequency responsive indicatingdevices, means including a step by step selector switch for successivelyconnectingsaid indicating devices to the channel, said switch having aplurality of positions and a stepping magnet, means responsive to aninterruption in current in said channel to energize said magnet, andtime delay means for deenergizing said magnet before the initiation ofthe succeeding impulse, said switch being arranged to operate to thenext position in response to deehergization of said magnet.

5. The combination, in a carrier current telemetering system, in whichcarrier impulses are transmitted to a remote point, .each impulse beingmodulated with current having a frequency determined in accordance withthe position of an element to be indicated at said remote point, of acarrier current detector at said remote point, a plurality of frequencyresponsive indicating devices at said point, step by step switchingmeans for successively connecting said indicating means to saiddetector, said switching means including a stepping magnet, timeresponsive means, means responsive to an interruption in the supply ofcarrier current to said detector for energizing said magnet and saidtime responsive means, said time responsive means being operable todeenergize said magnet after a predetermined time interval and beforeinitiation of a succeeding impulse, and additional means responsive toan interruption of longer duration for causing said switching means tobe operated to a predetermined position.

6. The combination, in a telemetric system in which current impulses aretransmitted through a telemetering channel, each impulse having afrequency determined in accordance with the position of an element to beremotely indicated, of a plurality of frequency responsive indicatingdevices, means including a step-by-step selector switch for successivelyconnecting said indicating devices to said channel, said switch having aplurality of positions and a stepping magnet, means responsive to a timeinterval longer than those occurring between successive impulses forrestoring said selector switch to a predetermined position, said firstmeans including a time responsive means and means responsive to thetermination of any impulse for energizing said stepping magnet and saidtime responsive means, said time responsive means operating after anyimpulse to deenergize said magnet after a predetermined time intervaland before the initiation of a succeeding impulse.

7. The combination, in a telemetric system wherein carrier currentimpulses are transmitted through a telemetric channel, each impulsebeing modulated with current having a frequency determined in accordancewith the positionof an element to be remotelyindicated, of a carriercurrent detector, a plurality of frequency responsive indicatingdevices, step-by-step switching means for successively connecting saidindicating devices to said detector during the time interval betweensaid impulses, means energized upon initiation of said impulses andresponsive to a time interval greater than that between said impulses,an additional time responsive means, a stepping magnet for said switch,and means responsive to the termination of an impulse for energizingsaid stepping magnet and said additional time responsive means, saidadditional time responsive means operating to deenergize said magnetafter a predetermined time interval and before initiation of asucceeding impulse, said first means in cooperation with said additionaltime responsive means operating to restore said switch to its originalposition in re- 1 sponse to a time interval in excess of that betweensaid impulses.

CHARLES S. FRANKLIN.

